I've run your test program and it receives fine for me. I note that the source address is not on the same subnet as (any of) the receiver's addresses. Are the packets being routed? The default multicasting TTL is 1, though I don't know if it'll be checked or dropped on the receiver, seeing as we aren't forwarding it.
Also, you might want to run "netstat -s" to see if any of the drop counters are being incremented (e.g., checksum error). Finally, I'm assuming you don't have any firewall rules that are matching, right? +-DLS - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html